IAEA Certified Reference Materials Research Articles

Simultaneous determination of 226Ra and 228Ra in food samples using liquid scintillation counting

The 228Ra and 226Ra isotopes of radium are significant contaminants in food, raising public concern because of their radiotoxicity. Several methods are available for determining 228Ra and 226Ra. However, the application of these procedures is not focused on food but only on water and environmental matrices. In this study, a cost-effective method for the simultaneous determination of 226Ra and 228Ra radioactivity in food samples using liquid scintillation counting was developed. The overall efficiencies of 226Ra and 228Ra in the food samples are 69.4–78.4% and 30.1–35.8%, respectively. The minimum detectable activities of 226Ra and 228Ra are 11.3 mBq/g and 33.4 mBq/g, respectively, in our food sample, obtained using a 1.0 g ash sample and 60 min of counting time. The method was validated using IAEA-certified reference materials and compared with data obtained using gamma spectrometry in tea, kelp, and oyster samples.

Rapid and reliable assaying of Tc-99 in sediment samples with novel MTPN polymeric resin

The paper describes a new method for the rapid determination of Technetium (Tc) in sediment samples using solid-phase extraction chromatography (SPEC) with a novel methyl triphenyl phosphoniumnitrate (MTPN) resin. The effectiveness of the resin in selectively recovering Tc was evaluated in both batch and column mode and exploited for rapid analysis of ’Tc’. The procedure involves the acid digestion of samples, pre-concentration of fission products in supernatant and co-precipitation of actinides with Fe(OH)3, followed by selective recovery of Tc by SPEC using a column filled with MTPN resin. The recovered Tc was then radiometrically assayed using beta counting. The method was validated using IAEA certified reference materials and was found to provide reliable and reproducible results for the activity concentration of Tc-99 in sediment samples within 24 h.

Simultaneous determination of 210Pb and 210Po in seafood samples using liquid scintillation counting

The measurement of 210Pb and 210Po in seafood samples has attracted tremendous interest because of their radiotoxicity. In this study, a fast and cost-efficient method for the simultaneous determination of 210Pb and 210Po in seafood samples by ultralow-level liquid scintillation counting after separation on a Sr•spec column was developed. The recoveries of 210Pb and 210Po were ~70% and ~85%, respectively. The minimum detectable activity of the proposed method for 210Pb and 210Po was 3.85 Bq/kg and 1.50 Bq/kg, respectively, which is suitable for the determination of 210Pb and 210Po in seafood samples. The radiochemical procedure was validated by measuring 210Pb and 210Po activity concentrations in IAEA-certified reference materials and successfully applied to shrimp and clam samples.

A procedure for the sequential determination of radionuclides in soil and sediment samples

We present a new radiochemical procedure for the sequential determination of Sr, Am, Pu, Th and U radionuclides. For the validation, seven IAEA certified reference materials were analyzed for 239Pu, 240Pu, 241Pu, 238U and 232Th isotopes by ICP-MS, 243Am by alpha spectrometry and 90Sr by low level gas proportional counting. The sequential method was then used for determining the radionuclide profiles in one sediment core collected in the River Rhine, near Augst, downstream of the Swiss nuclear power plants.

A sequential determination of 90Sr and 210Po in food samples.

The latest EU Council Regulation 2016/52/Euratom updates the emergency limits on radionuclides in foods including 210Po and 90Sr, two of the most important radionuclides for radiological dose from the ingestion pathway. A novel and straightforward method has been developed for sequential determination of 90Sr and 210Po in food samples using ultra low-level liquid scintillation counting and alpha-particle spectrometry. For 90Sr analysis, the method makes use of stable strontium as yield tracer, and 210Po is determined through self-deposition using 209Po as a yield tracer. The quantification limit for this method is 25.0 and 2.0Bqkg-1 for 90Sr and 210Po, respectively. The proposed radiochemical separation can be completed within 2days for a batch of 12 samples. The radiochemical procedure was validated by its application for the measurement of IAEA certified reference materials, and through participation in a national intercomparison exercise. Results are also presented in seafood from the Mediterranean coast.

Actinide measurements by AMS using fluoride matrices

Actinides can be measured by alpha spectroscopy (AS), mass spectroscopy or accelerator mass spectrometry (AMS). We tested a simple method to separate Pu and Am isotopes from the sample matrix using a single extraction chromatography column. The actinides in the column eluent were then measured by AS or AMS using a fluoride target matrix. Pu and Am were coprecipitated with NdF3. The strongest AMS beams of Pu and Am were produced when there was a large excess of fluoride donor atoms in the target and the NdF3 precipitates were diluted about 6–8 fold with PbF2. The measured concentrations of 239,240Pu and 241Am agreed with the concentrations in standards of known activity and with two IAEA certified reference materials. Measurements of 239,240Pu and 241Am made at A.E. Lalonde AMS Laboratory agree, within their statistical uncertainty, with independent measurements made using the IsoTrace AMS system. This work demonstrated that fluoride targets can produce reliable beams of actinide anions and that the measurement of actinides using fluorides agree with published values in certified reference materials.

Investigate the capability of INAA absolute method to determine the concentrations of 238U and 232Th in rock samples

This work aimed to study the capability of INAA absolute method in determining the elemental concentration of 238U and 232Th in the rock samples. The INAA absolute method was implemented in PUSPATI TRIGA Mark II research reactor, Malaysian Nuclear Agency (NM). The accuracy of INAA absolute method was performed by analyzing the IAEA certified reference material (CRM) Soil-7. The analytical results showed the deviations between experimental and certified values were mostly less than 10 % with Z-score in most cases less than 1. In general, the results of analysed CRM Soil-7 show a good agreement between certified and experimental results which mean that the INAA absolute method can be used accurately for elemental analysis of uranium and thorium in various types of samples. The concentration of 238U and 232Th ranged from 1.77 to 24.25 and 0.88 to 95.50 ppm respectively. The highest value of 238U and 232Th was recorded for granite rock sample G17 of 238U and sample G9 of 232Th, whereas the lower value was 1.77 ppm of 238U recorded in sandstone rock and 0.88 ppm of 232Th for gabbro. Moreover, a comparison of the 238U and 232Th results obtained by the INAA absolute method shows an acceptable level of consistency with those obtained by the INAA relative method.

Determination of 90Sr in milk and milk powder in Tehran and estimation of annual effective dose

Thirty-eight different milk and milk powder samples from Tehran-Iran were collected and analyzed for 90Sr activity using a method in which the daughter product of 90Sr decay (90Y) was extracted by tributyl phosphate from ashed milk. 90Y was then back extracted with water, and oxalate was precipitated . Following the sample analyzing, beta counting was performed with an ultralow-level liquid scintillation spectrometer. The quality control and assurance of the method were obtained by standard samples prepared with an IAEA-certified reference material. The mean determined 90Sr activity concentration in the analyzed milk and milk powder (0.225 ± 0.042 and 0.216 ± 0.024 Bq kg−1, respectively) showed that the radioactivity concentration in our samples was too low to induce biological hazards. These data can provide useful information of the background level of contamination, which in turn can be used in the following environmental monitoring programs.

Calcium Supplements: an Additional Source of Lead Contamination

The risk posed by the quantity of heavy metal lead present in Ca supplements is of grave concern. Some lead levels have been measured up to the extent of regulatory limit set by the United States. Calcium supplements inevitably get contaminated with lead as both are naturally occurring elements having the same charge density. Therefore, it is imperative to indicate the level of this toxic metal in these supplements in order to create awareness among consumers. The calcium in the supplements is derived from natural as well as synthetic/refined sources (chelated or non-chelated). In this study, a sophisticated analytical technique, atomic absorption spectrometer (both with FAAS and GFAAS modes of atomization), was used for the purpose of analyzing Pb contents in 27 commonly used Ca supplements manufactured by different national and multinational companies. The daily intake of lead through these supplements was calculated. Only 10% of the calcium supplements analyzed met the criteria of acceptable Pb levels (1.5 μg/daily dose) in supplements/consumer products set by the United States. It was also found that Pb intake was highest in chelated calcium supplements whereas lowest through calcium supplements with vitamin D formulation. The Pb concentration in calcium supplements was significantly increased (p < 0.001) according to their composition. In order to validate our results from the study conducted, IAEA-certified reference material (animal bone, H-5) was analyzed for Pb levels. The limit of detection of the method used was 0.05 μg/g and a 95% lead recovery of IAEA-certified reference material (animal bone, H-5).

Determination of trace elements in porcine brain by inductively coupled plasma-mass spectrometry, electrothermal atomic absorption spectrometry, and instrumental neutron activation analysis

Methods have been developed for the analyses of trace metals in various areas of porcine brains, (temporal, parietal, frontal cortex, both right and left hemispheres). Determinations were carried out using inductively coupled plasma-mass spectrometry (ICP-MS) and electrothermal atomic absorption spectrometry (ETAAS). The elements investigated were Li, Mn, Cu, Zn, Cd, Hg, and Pb by ICP-MS and Cu, Cd, and Mn by ETAAS. For determination by ICP-MS, a method of standard additions calibration coupled with internal standards was used, and for ETAAS, standard additions calibrations were prepared. The accuracy of all methods was determined using NIST and IAEA certified reference material. A small number of pig brains were analyzed by instrumental neutron activation analysis for Cr, Co, Cs, Fe, Rb, Se, Sc, Sb, and Zn using the comparator method of analysis. Four separate NIST standard reference materials have been used to examine the validity of the comparator method.

Application of reference materials in the accurate calibration of the detection efficiency of a low-level gamma-ray spectrometry assembly for environmental samples

A new assembly dedicated for the low-level ψ-ray spectrometric measurements of environmental samples have been installed recently at the International Atomic Energy Agency's Laboratories, Seibersdorf. Calibration of the detection efficiency was performed by a set of 14 IAEA Certified Reference Materials, a standardized solution of134Cs, solutions of 2 pure potassium salts, and 2 mixed radionuclide gamma reference standard solutions. These materials, in 1.3 liter Marinelli beakers, were measured by a large HPGe detector. The high precision and accuracy of the calibration procedure is shown by the high significance achieved in the linear fits of the efficiency results, which are traceable to certified and standard reference materials. Small biases between some calibrands were detected. A new corrected result is the 1.37±0.05 Bq/kg activity concentration of137Cs in IAEA-A-14 Milk Powder.

A simple radiochemical determination of90Sr in environmental samples

A simple procedure for the determination of90Sr in environmental samples is described. The method uses the different solubilities of the oxalates of calcium and strontium in presence of a large excess of calcium. For this reason the method is especially suited for Ca-rich samples, as e.g., bones or soils. However, after addition of supplementary calcium it works equally well for other types of samples. The method was tested by analyzing the IAEA Certified Reference Materials soil, animal bone and algae.

Accuracy of multi-element analysis of human tissue obtained at autopsy using inductively coupled plasma mass spectrometry

The accuracy of inductively coupled plasma mass spectrometry (ICP-MS) for the multi-element analysis of human tissue has been assessed by analysis of National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 1577a Bovine Liver, International Atomic Energy (IAEA) Certified Reference Material (CRM) H 8 Kidney and IAEA CRM H 4 Animal Muscle for Al, Mg, Mn, Fe, Co, Zn, Cu, Mo, Rb, Sr and Cd. Twenty three out of 24 determinations agreed with certified values. An intercomparison was also made between ICP-MS and the well established technique of atomic absorption spectrometry (AAS) for Al, Mg, Mn, Fe, Cu, Zn and Cd in human tissue samples, which covered a much wider range of analyte concentrations than the reference materials. Drift in the ICP-MS instrument was studied for 3 h and all but the lighter elements Al and Mg were found to be acceptably controlled by an In internal standard. The equivalence of the ICP-MS and AAS data was compared using the usual statistics of correlation and regression. In addition, comparisons were made using the statistical analysis advocated by Bland and Altman. In spite of the problems found, ICP-MS is capable of accurate and rapid multi-element analysis of human autopsy tissue.

Frequency of concentrations of some trace elements in serum by INAA

Concentration levels of eight trace elements in 120 samples of human blood serum were investigated by Instrumental Neutron Activation Analysis (INAA) for the purpose of medical research. The elements Co, Cr, Cs, Fe, Rb, Sc, Se, and Zn were simultaneously determined by the relative method in comparison with inorganic standards treated under identical conditions. The process of analysis and its reliability was checked using human serum and IAEA certified reference material. Statistical results are expressed in ppm or ppb. Both normal and, if necessary, log-normal frequency distributions of all elements determined are presented, types of distribution curves are verified statistically on 95% level of probability.

Frequency of concentrations of some trace elements in scalp hair by INAA

126 samples of scalp hair from inhabitants of Central Bohemia were searched for content of zinc, cobalt, cesium, chromium, scandium, selenium, and iron, for the purpose of medical research. Simultaneous determination of the elements was made by INAA. Inorganic standards were used for calculation of concentrations of elements. Quality assurance was checked by IAEA certified reference material and by internal standard mixed human serum. Statistical results are expressed in ppm, or ppb. Both normal and, if necessary, log-normal distributions of elements are presented, and types of distribution curves are verified statistically on 95% level of probability.